Electric switch.



W. B. CROSSLAND.

ELECTRIC SWITCH.

APPLICATION FILED APR. 9. 1915.

1,1 9 1 ,284. Patented July 18, 1916.

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W. B. CROSSLAND.

ELECTRIC SWITCH.

APPLICATION FILED APR. 9. 1915.

1,19 1 ,284. v Patented July 18, 1916.

4 SHEETS-SHEET 2.

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W. B. CROSSLAND.

ELECTRIC SWITCH;

APPLICATION men APR. 9. I915.

Patented July 18, 1916.

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W. B. CROSSLAND.

ELECTRIC SWITCH.

APPLICATION FILED APR. 9. 19:5.

Patented July 18, 1916 4 SHEETS-SHEET 4.

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UNITED STATES WILLIAM BLACKNELL CROSSLAND, OF NEWPORT, ARKANSAS.

ELECTRIC SWITCH.

Specification of Letters Patent.

Patented July 18, 1916.

Application filed April 9, 1915. Serial No. 20,263.

To all whom it may concern Be it known that I, WILLIAM B. Cnoss- LAND, a citizen of the United States, residing at Newport, in the county of Jackson and State of Arkansas, have invented a new and useful Electric Switch, of which the following is a specification.

This invention has reference to electric switches and its object is to provide an electric switch whereby the circuit is completed or opened, as the case may be, in a gradual manner entirely beyond the volition of the operator.

The present invention while adapted to the control of circuits carrying either large or small currents is particularly designed for use in connection with circuits carrying small currents, although the voltage may be that of ordinary street currents or higher.

In accordance with the present invention there is provided a liquid resistance and a movable element which may be gradually immersed in or withdrawn from the liquid element, or the liquid may be caused to flow in a manner to gradually rise on the conducting element so that the current is gradually applied or the circuit is gradually broken, thus in either instance avoiding any sudden umps in potential.

The present invention is susceptible of manufacture in such small sizes as to occupy but little if any more space than an ordinary wall switch where a circuit is suddenly closed or suddenly opened. A sudden closure of the circuit and a sudden throwing on to certain types of electric translating devices of the full or normal voltage produces an abnormal heating effect, this being particularly noticeable in the case of tungsten lamps. In such lamps the filament when cold is of so much lower resistancethan when hot that the sudden throwing on of a current of, say, one hundred and ten .volts, causes a sudden jerk or movement of the filament which is due to the sudden expansion incident to the heating effect of the current. If the filaments be at all imperfect a few such violent jerks become destructive, and even in the case of perfect filaments the life and brilliancy of the lamps are greatly reduced after a short term of service, so that the full-efficiency life of the lamps is correspondingly reduced. By a gradual increase in the voltage in charging the l p rcu t all d ge o i bili y of damage to the filaments is avoided, since the filaments heat relatively slowly and the life and brilliancy of the filaments are maintained to the greatest possible extent. The gradual cutting out of the lamp has also been found to be conducive to the prolongation of the life and the maintenance of the brilliancy of the lamp.

The invention will be best understood from a consideration of the following detailed description, taken in connection with the accompanying drawings forming a part of this specification, with the further understanding that while the drawings show a practical form of the invention, the latter is not confined to any strict conformity with the showing of the drawings, but may be changed and modified so long as such changes and modifications mark no material departure from the salient features of the invention.

I11 the drawings :Figure 1 is a vertical longitudinal section with some parts in elevation of an electric wall switch embodying the present invention. Fig. 2 is a section on the line 22 of Fig. 1. Fig. 3 is a section on the line 33 of Fig. 1. Fig. 41 is a vertical longitudinal section of another embodiment of the invention. Fig. 5 is a sec tion on the line 55 of Fig. 4. Fig. 6 is a section on the line 6.6 of Fig. 1. Fig. 7 is a longitudinal vertical section of another form of the invention. Fig. 8 is a section on the line 8 8 of Fig. 7. Fig. 9 is a view of a stop device. Fig. 10 is a section similar to Fig. 1. but showing a different form of temporarystop, and another form of tapering conducting element. Fig. 11 is a section on the line 11-11 of Fig. 10 with some distant parts omitted. Fig. 12 is a section on the line 1212 of Fig. 10. Fig. 13 is, a perspective view of the form of ta per conducting element shown in Figs. 10 and 12. Fig. 14l. is anend elevation of a one-piece tapering conducting element.

Referring first to the structure of Figs. 1, 2 and 3, there is shown a box or casing 1 which may conform in general structure to boxes as usually constructed for wall switches. The box is open at one end and is there provided with ears 2, whereby the box may be fastened to a wall. by means of screws 3 or otherwise. Furthermore, the open or front end of the box is supplied with a face plate 4; which may conform in general construction to the face plates usually provided for the boxes designed to contain wall switches.

While the box 1 of the present invention may be provided with knocleouts, as is customary, such knock-outs are not shown, since it is not deemed needtul to show them.

The box has a removable rear end and secured to this end is a bearing block (3 and, considering the box as of metal, the bearing (l is insulated from the box by insulating material 7. Fast to the face plate 4- in alinement with the hearing (3 is another bearing 8 separated electrically from the face plate -I by insulating material 9. The reason for insulating the bearings (3 and S iirom the respective parts carrying them is to permit the use of these bearing tor the connection 01 electric conductors thereto. The bearing 6 l as a conductra' 10 made fast thereto by a binding screw 11 or otherwise, and the hearing 8 has a conductor 12 made fast thereto by a binding screw 13 or otherwise.

ll ithin the box there is a cylinder 1'l ot hard rubber or other suitable insulating material, and applied to the ends of the cylinder are heads 15 and 16, respectively, which heads may, if desired, be made of metal. The head 17) carries a short spindle 17 adapted to the bearing 6, and the head 16 carries a longer spindle 18 extending through the bearing 8 to and beyond the exterior face of the face plate 1 where the spindle 1 is supplied with a manipulating knob or handle 19 in position to be readily accessible to any one desiring to manipulate the switch. The continuity of the spindle 18 is broken and the spindle is insulated from the head 16. as shown in Fig. 10, in a manner and tor a purpose to be described.

The cylinder 11 is provided with an axial diaphragm 20 dividing the cylinder into two chambers 21. 22, which may be 01 equal size, although this not strictly obligatory. The diaphragm 21) has perforations 23 therethrough. so that the two chambers 21 and 22 are at all times in communication, but such communication is restricted by the size and number oil the perforations. The cylinder 11 contains liquid indicated at 24', which liquid may be of relatively poor conducting qualities for the current for which the device is intended. The conductivity of the liquid 9t. which may be termed a liquid resistance, is so adjusted that in the length of the cylinder let the amount of current which will traverse it becomes a negligible minimum.

Mounted on, but insulated from the head 16 and directed toward the head 15.is a conducting element 25 gradually diminishing in breadth or thickness or both from one end toward the other, so that it may be described as generally tapering. The element may conveniently be made of metal and is electrically connected to the spindle 18.

It is shown as conforming in general to the circular shape of the cylinder 11-, but is only continued circumterentially sulliciently to be lodged in one of the chambers, say, the chamber While the conducting element has been described as carried by the head 16 it might, of course be just as well carried by the head 15.

The amount of liquid 21 within the cylinder 14 is such that when the cylinder is turned so as to bring the compartment 22 below the compartment "31 with the diaphragm :"20 horizontal, or approximately so, the conducting element 25 is immersed in the liquid 21 to practically its tall extent. The large end 01 the conducting element 25 is close to the bottom of the cylinder when the compartment or chamber lowermost, and the small end of the element is in close relation to the head remote from that carrying the element. which remote head in the particular showing of the drawing is the head 15. It it be considered that the conducting element 25 is immersed to the full extent provided in the liquid resistance 24, current reaching the head 1:) will find the least amount o'l liquid resistance ilin its path to the conducting elements 25 and from the latter to the spindle 18. In such event the circuit between the conductors 1t) and 12 may be considered as closed through the liquid resistance 21- and practically all of the conducting element 25 to and by way of the spindle 1S and bearing 8 to which the conductor 19 is connected. Under such circumstances the path 01. the current is through a minimum amount of the liquid resistance 21 and as the resistance of the conducting element 25 is negligible it may be considered that the amount of current flowing from the conductor 10 to the conductor 12 very closely pproaches the full current demanded by the translating devices. lit. now. the cylinder 1-1 be turned so that the chamber 22 is uppermost and the chaml'ier 21 is below the diaphragm 20, the liquid 21 gravitates through the passages or perforations 23 soon leaving the element 25 without any electrical connection with the head 15, wherefore all current ceases and the switch is open. This opening of the switch, however. is not a sudden opening, but takes an appreciable time because the liquid 91- finds its way but slowly from one compartment to the other i and the conducting element 25 becomes but slowly freed from the liquid 91. wherefore there is offered to the passage of the current a gradually increasing resistance preventing any sudden changes of the potential, or sudden fluctuations of current such as occurs in ordinary switches. and especially in ordinary snap switches.

If it be considered that the compartment 22 is uppermost and the compartment 21 is lowermost and contains the liquid 24, a turning of the cylinder 14 to reverse the positions of the two compartments causes an elevation of the liquid 24 with the compartment 21, so that the liquid gravitates through the perforations 23 into the compartment 22 then lowermost, which compartment contains the tapering conducting element 25. Now, the liquid accumulates in the compartment 22 by gravitating from the compartment 21 and first engages the conducting element at its shorter end, so that the path of the current from the head 15 to the spindle 18 is by way of a relatively long body of resistance and a relatively short length of good conductor. This relation, however, gradually changes by the accumulation of the liquid 24 in the compartment 22, thus similarly reducing the path of the current through resistance and increasing the path of the current through good conductor, until finally the liquid reaches its highest level where there is a very short eX- tent of resistance and a relatively great extent of good conductor, so that when such condition is finally attained nearly all of the resistance has been eliminated.

WVithin the box 1 upon the spindle 18 is a. mutilated pinion 26 normally in engagement with a sliding rack bar 27 mounted to slide in a frame 28. In the particular show ing of Figs. 1 and 2 the rack bar 27 is upright and moves up and down, while the frame 28 is also upright. In the path of the lower end of the rack bar 27 is a contact block 29 fast on but insulated from the box 1 and the lower end of the rack bar is formed into a contact 30 adapted to make engagement with the contact block 29. The rack bar near its lower end carries a collar or flange 31 against which bears one end of a spring 32 surrounding the rack bar and hearing at its other end. against the frame 28, the tendency of the spring 32 being to maintain the contact 30 in engagement with the contact 29 and the rack bar in the low ered position. Carried by the collar 31 is another rack bar 33 spaced from but parallel with the rack bar 27 and extending through the top of the frame 28. In the path of the teeth of the rack bar 33 is a gear wheel 34 mounted on a post 35 upstanding from the frame 28. The rack bar has a smooth or toothless end 36 so arranged that when the rack bar 27 is near to its lowermost posi tion, the teeth of the rack bar- 33 are no longer in engagement with the gear wheel 34. This gear wheel is shown as in mesh with a pinion 37 so as to impart rapid rotation thereto, and this pinion is provided with fan blades 38 for retarding its rotation in the same manner as retarding devices employed in connection with striker move ments of clocks.

The rack bar 27 has a binding screw 39 at its upper end for the attachment thereto of one end of a conductor 40 branched off from the conductor 12. There is also a conductor 41 branched off from the conductor 10 and connected to the contact 29. Within the comparti'nent 21 of the cylinder 14 is a vent tube 42 so arranged as to provide for the inlet of air to the cylinder or the escape of gases therefrom, but preventing the escape of liquid from the cylinder. If the end 30 of the rack bar 27 is in engagement with the contct block 29, the resistance element comprising the liquid 24 and the conducting element 25 is short circuited, wherefore the current has a path relatively free from resistance about the resistance device included in the box 1. When the knob 19 is manipulated to rotate the spindle 18 and with it the cylinder 14, the teeth on the mutilated pinion 26 engage the teeth of the rack bar 27 and cause the latter to rise, at the same time compressing the spring 32. Immediately after the rack bar 27 begins to rise the teeth of the rack bar 33 are brought into engagement with the gear wheel 34, whereupon the gear wheel is rotated, but its movement is resisted by the action of the fan blades 38. These fan blades rotate rapidly, since the pinion 37 is small as compared with the gear wheel 34, and so offer considerable resistance to the rising movement of the rack bar 27. Because of this the cylinder 14 is turned from the circuit-closing position but slowly. As soon as the rack bar 27 begins to move in the manner just stated,

the circuit between the conductors 10 and 12 by way of the respective branch conductors 41 and 40 is broken at the contacts 29 and 30, so that the resistance device is no longer short-circuited, but the course of the current taining the liquid and conducting element 71 25, is rotated until above the compartment 21 from which latter it is separated by the diaphragm 20 and the liquid 24 flows through the perforations into the then lower compartment 21. Ultimately all the liquid 24 gravitates from the compart ment 2 into the compartment 21 and is no longer in engagement with the conducting element 24, so that the circuit between the conductors 10 and 12 is then broken. break, however, is slowly brought about by the retarded flow of the liquid away from the conducting element 25 in a manner causing a progressively less amount of the conductor 25 to be in the circuit, until before the liquid finally leaves the conducting elcment 25 suflicient resistance has been intro duced into the circuit to greatly reduce the current, so that on the instant of break but a very small fractional portion of the normal.

The

current is flowing and there is no harmful effect produced by the break of the circuit.

The attainment of the rack bar 27 to the high point representing the position of the cylinder 14 where the compartment 22 is above the compartment 2l may be indicated by a stop or click of any appropriate construction, a very simple form being illustrated. Such simple form consists in providing a spring finger l3 mounted on the frame 2Q alongside of the rack bar 27 and carrying at its free end a tooth -l-l; adapted to enter a notch 45 in the rack bar when the latter has reached its highest point. The tooth l-t and notch l5 are so related that a force tending to move the rack bar downwardly, which force should be greater than the expansive force of the spring 32, will cause the tooth ft to ride out of the notch. In this way the knob 19 may be turned to open the circuit, and when it has reached its limit of movement the feel of the tooth er dropping into the notch apprises the operator that the parts are in the open circuit position. \Vhcn it is desired to close the circuit the direction of rotation of the knob 19 may be reversed, whereupon the then uppermost compartment is lowered, and the compartment 21 then containing the liquid is raised to the high position, so that the liquid gravitates through the perforations 2 3 and slowly rises on the conducting element 25, thereby progressively cutting out or lessening the amount of resistance in the circuit. The lowering movement of the rack bar is retarded by the fan 38. The retardation thus introduced into the movement of the parts to the closed circuit position is properly timed to permit a progressive cut ting out of the resistance by the encroachment of the liquid 2% on the conducting element until by the time the rack bar 33 has reached that point with relation to the gear wheel 34; to run oli' therefrom by bring ing the smooth part- 36 opposite the wheel 3t only the smallest amount of the resistance lluid Ql is then located between the head and the conducting element 25, wherefore when the rack bar 33 runs oil from the gear wheel 3 and the expansion of the spring 232 causes a quick closure of the circuit at the contacts and and the consequent short-circuiting of the resistance element there is but a negligible increase in the amount of current directed through the lamp or other translating device.

In Figs. l, 5 and (3 a similar arrangement so far as function is concerned is illustrated. Mounted on a base $6 is an upright vessel -tT which may be of glass or other insulating material. and this vessel at its upper end is provided with a cap or head l8 having a central axial boss 1 9 traversed by a rack bar 50. That end of the rack bar within the vessel -l-T carries an expanded head 51 to which is attached one end of a cylinder 52 of insulating material, the other end of the cylinder being closed by a head 53 provided with a central perforation or passage Carried by and in pendent relation to the head 51 and located within the cylinder is a tapering conducting element 55 similar to the conducting element 28 of Fi g. 1. The base l6 is of conducting material either in whole or in part, and rising axially from the base T6 is a post or rod 56 so positioned as to extend through the passage 54c when the rack bar is lowered and the cylinder with the heads 51 and participating in such movement. lVithin the casing 4:7 is liquid resistance 57. \Vhen the rack bar, together with the casing and parts carried thereby, is lowered the entrance of the resistance liquid 57 into the interior of the casing is retarded by the side of the passage 5-.l, which passage is more or less throttled by the rod 56 at the time extending through the passage. The result of this is that buoyancy of the cylinder will resist lowering movement, and this may be further controlled by a vent hole 58 in the head 51. By making the rack bar 50 and heads -l-S and 51 of conducting material, such as metal, and also making the rod 56 of conducting material, such as metal, and also making the rod 56 long enough, the conducting element is short-circuited when the head .51 is brought into engagement with the upper end of the rod 56. Erected on the head -18 is a post or upright 59 carrying a casing 60 in i.

38. The shaft 61 exterior to the casing (30 is provided with a gear wheel (36 and manipulating knob or finger piece (37. The gear wheel ()(3 is in mesh with the teeth of the rack bar 50. The base l6 carries a binding post (38 or other means of connecting it in circuit, and the head 48 is provided with a binding post (39 or other means for connecting it in circuit. lVhen the cylinder 52- is above the level of the resistance liquid 57 the circuit between the binding posts 8 and (S9 is broken. As soon as the cylinder is lowered suiiiciently so that the liquid 57 may enter through the passage 54: into the cylinder and rise therein to an extent sullicient to reach the conducting element 55 curclose to the head 51. Under these circumstances nearly the maximum current is flowing and the final movement of the rack bar and cylinder or container then brings the head 51 and rod 50 in contact, thus providing a shunt circuit of practically negligible resistance around the resistance element, so that the full current then passes between the binding posts 68 and (i9 and the resistance element is in effect cut out. On the reverse movement of the rack bar 50 the resistance is progressively introduced so that on the final complete break of the circuit the current has been reduced to a negligible minimum and no arcing or destructive sparking can occur. Both the closing and opening movements are retarded So that the operator must close or open the circuit deliberately, thus giving time for the cutting out or introduction of resistance, as the case may be, in such manner that there can be no violent surges of current.

In Fig. 7 and associated figures another modification of the invention is illustrated. Erected on a base 70 are uprights 71, 72 and H (3 suitably spaced. apart. Extending between and carried by the uprights 71 and 72 is a casing 74 which may be of cylindrical form, although such form is not mandatory, but for convenience of description the casing 74 may be termed a cylinder without limitation to such particular form. At one end the cylinder 74 is provided with a head 75 of conducting material, such as metal, and at the other end with a head 7 G, which also may be of metal. Within the cylinder 7 4, and by preference carried by but insulated from the head 75 is a conducting element 77 of taper form like the conducting elements 28 and 55 already referred to. This conducting element 77 is carried by the head 75 in the upper part of the cylinder 74 and the taper edge of the element 77 slants upwardly from the head 75 toward the head 76. The cylinder 74 is supported in the standard or upright 71 by a spindle 78 which may be sepa rated from the standard 71 by an insulating bushing 79 although this is not absolutely essential. Arranged on the element- 7 7 is a binding post 80. The cylinder 74 is provided with a filling plug 81. having a vent 82 there through. The head 7 G is connected to the standard or upright 72 by a short threaded nipple 83 having a passage 84 therethrough, but, of course, other connections than a nipple connection may be provided. Extending through the upright or standard 73 preferably in line with the spindle 78 and nipple 83 is a rod 85 carrying between the standards 72 and 73 a follower 86 which may be of similar height and breadth to the upright or standard 72. Connected at the ends to the standards 72 and 86 is a bellows-like casing 87 which is so constructed as to expand and collapse as the follower 86 1s moved from or toward the standard 72. Between the standards 73 and the follower 82 the rod 85 is surrounded by a spring 88 tending to move the follower 86 toward the standard 72 but yieldable to a force applied to the rod to move the follower in the opposite direction. To apply such force the rod 85 terminates in a knob or handle 89. The follower 86 car ries at its upper end a contact 90 provided with a binding post 91 and the standard 72 carries a contact 92 provided with a binding post 93. The contacts 90 and 92 are arranged to enter one into the other to insure good contact without sticking. The cylinder 74 and casing 87 are supplied with a suitable quantity of liquid resistance 94, which, when the follower 8G is drawn away from the upright 72, may fill the cylinders 74 and 87 to about the level of the passage 84. 2 When, however, the follower 86 is moved toward the upright 72 the effective capacity of the casing 87 is reduced and the level. of the resistance liquid within the casing 87 rises until it overflows through the passage 84 into the cylinder 74 and adding to the liquid already therein the level of the liquid resistance within the cylinder 74 is elevated until it reaches that end of the tapering conducting element 77 remote from the head 76. As the liquid rises in the cylinder 74 it progresses along the conducting element 77 in a direction toward the head 7 6, thus reducing the amount of liquid resistance which must be traversed by the current in passing between the head 75 and port 80, all as in the forms already described. I

lVith the structure of Fig. 7 and associated figures the line conductors are connected to the binding posts 80 and 93, while the line conductors 95, 96 are connected to the binding posts 80 and 93, respectively, and a branch conductor 97 connects the binding posts 80 and 91. The parts are so proportioned that when the follower 8G is moved away from the upright 72 a sufficient distance, the level of the liquid 94 within the cylinder 74 is below the lowermost part of the conducting element 77 and the contacts 90 and 92 are correspondingly separated.

When the follower 86 is moved toward the upright 72, the liquid 94 within the casing 87 is forced into the cylinder 7 4 and the liquid in the latter rises until it makes progressive contact with the conducting element 77 and the resistance between the heads 75 and 76 is progressively lowered, so that more and more current finds its way from the conductor 95 to the conductor 96 and ultimately the resistance is short circuited by the engagement of the contacts 90 and 92. The follower S6 is moved slowly away from the upright 72, quick movement being prevented by the resistance offered to the flow of liquid through the contracted passage 84. The return movement of the follower 86 toward the standard 72 may be caused by the spring 88, but this movement is of course relatively slow because of the contracted passage 84.

The three examples given of different forms which the invention may assume makes it evident that the invention is susceptible of practical embodiment in many forms other than the three examples given, for which reason the invention is not limited in its practical form to the particular embodiments shown.

Different resistance liquids are adaptable to the variable resistance switch of the present invention, and among such liquids may be mentioned saline solutions and acidulated water.

In the structure of Figs. 1, 4c and 7 the conducting elements 25, 55 and 77 are shown as curved in cross-section and corrugated, but these conducting elements may be variously made, as, for instance, the conducting element as shown at 98 in Figs. and 12 is made up of a series of tapering plates 99, so that the whole element 98 is circular in cross-section and tapers from one end to the other with the plates in parallel spaced relation. in Fig. 1 the element terminates at the larger end in plate 100 mounted on the head 10, but separated therefrom by insulation 101. In Fig. 10 the plates 99 are mounted on an end plate 100 like the plate 100 and separated from the head 16 by insulation 101.

In the structures of both Figs. 1 and 10 the plate 100 or 100, as the case may be, is carried by a section 18 of the spindle 18, this section extending through the head 10 from which it is electrically separated by an insulating bushing 102 held to the head by a nut 103 with an interposed washer 101.

For facilitating the removal of the cylindrical container 11 from the box or casing 1 and at the same time to cause rotation of the spindle 18 to impart like rotative movement to the cylinder l-l, the spindle section 18 terminates in an axially and laterally extended tongue 101i: adapted to a slot 105 in the corresponding end of the main body of the spindle 1S and where the tongue 10-1 enters the slot 105 there is a bearing 100 on the frame 28 holding the two parts of the spindle together. In Fig. 10 the bearing 100 carries a binding post 107 to receive the conductor 12.

111 Fig. 10 the spindle 18 is formed with an eccentric portion 108 to which is connected one end of a spring 109, the other end being connected to the frame 28. Also in Fig. 10 the spindle 108 is provided with a radial boss 110 having a notch 111 therein into which a nose 112 on a head 113 is adapted to seat. The head 113 is formed on or attached to one end of a rod 114: slidable in a bracket 115 fast to but insulated from the face plate 1, and a spring 116 surrounding the rod 11-1 imparts to the head 113 a constant constraint toward the boss 110.

In other respects the structure of Figs. 11, 12 and 13 is similar to the structure of Fig. 1, and where similar parts occur the same reference numerals are employed with respect to both figures and figures of drawing associated therewith.

The conducting element designated by the numerals 25, 55, 77 and 98 in the figures already described may be in the form of a block 117 as shown in Fig. 11, whether this block be solid or hollow.

The several examples of conducting elements show that it is quite feasible to make the conducting element in various forms, some of which may be different from those shown in the drawings, so that it is unnecessary to multiply examples. The essential feature of the conducting element is that as the liquid rises on it there is a progressive increase of conductivity, and as the liquid tlows away from it there is a progressive increase in resistance.

lVhat is claimed is 1. A variable resistance con'n'n'ising a vessel. adapted to contain a resistance liquid and provided with circuit terminals to be bridged by the resistance liquid, a tapering conducting element within the vessel permanently connected to one of the circuit terminals and having its taper cnd directed toward the other circuit terminal, and means for causing a relative progressive move ment of the liquid lengthwise of the tapering conducting element to correspondingly progressively decrease or incr ase the active amount of resistance liquid included in the circuit.

2. A variable resistance comprising a vessel adapted to contain a resistance liquid, a tapering conducting element within the vessel, and means for causing a relative progressive movement of the liquid lengthwise of the tapering conducting element to correspondingly progressively decrease or increase the active amount of resistance liquid included in the circuit, said variable resistance including circuit terminals independent of the tapering element and associated to make contact and short circuit the resistance on the attainment of the resistance to the minimum effective amount.

3. An adjustable rheostat device comprising a container for resistance liquid, said container having spaced conducting portions adapted to be electrically connected by the resistance liquid, a tapering conducting element in the container in association with the resistance liquid, and means for causing the liquid to engage the tapering portion of the conducting element in progression or retrogression to correspondingly reduce or increase the active amount of resistance liquid between the conducting portions of the container.

4. An adjustable rheostat structure comprising a container for a resistance liquid, said container having spaced conducting portions adapted to be electrically connected by the resistance liquid, a tapering conducting element within the container and carried by one of the conducting portions thereof and directed toward the other conducting portion, and means for causing the resistance liquid to encroach upon or recede from, the conducting element along the tapering portion thereof.

5. A variable resistance switch comprising a rotatable insulating casing having conducting ends, and an intermediate wall dividing the easing into two longitudinal con'ipartments with the division Wa1l=having passages therethrough, said casing con taining a resistance liquid and having in one of the compartments a tapering conducting element extending lengthwise of the con'rpartment, means for rotating the casing, and means for retarding the rotative movements.

6. A variable resistance switch comprising a rotatable insulating casing with conducting heads having connections for electric conductors, said casing having an intermediate longitudinal wall with passages therethrough dividing the easing into longitudinal communicating compartments, a tapering conducting element carried by one head and directed toward the other and located in one of the compartments, resistance liquid within the casing in quantity sufficient to substantially immerse the tapering conducting element, and means for rotating the casing to cause flow of the resistance fluid from either compartment into the other.

7. A variable resistance switch comprising a rotatable insulating casing with conducting heads having connections for electric conductors, said casing having an intermediate longitudinal wall with passages therethrough dividing the easing into longitudinal conmiunicating compartments, a tapering conducting element carried by one head and directed toward the other and located in one of the compartments, resistance liquid within the casing in quantity sufficient to substantially immerse the tapering conducting element, and means for rotating the casing to cause flow of the resistance fluid from either compartment into the other, said switch also including retarding means for slowing the rotative movements, and said retarding means including ing a cut-out for short circuiting the resistance.

8. A variable resistance switch comprising a rotatable casing having two longitudinal compartments adapted to contain resistance liquid and having a division wall with passages therethrough for retarding the flow of liquid from one compartment to the other, a tapering conducting element mounted in one cou'ipartment and extend ing longitudinally of said compartment, conducting heads for the casing with one of the heads carrying the conducting element, an arbor projecting axially from one head and provided with manipulating means, a mutilated gear wheel carried by the arbor, a rack bar engaged by the gear wheel and provided with means urging it in one direction, and said rack bar being provided with a circuit terminal, another circuit terminal in the path of the firstnamed circuit terminal, another rack bar carried by the first-named rack bar and a retarding gear train in position to be engaged by the second-named rack bar, and said second-named rack bar being of a length to escape from the gear train before the contacts engage.

9. A variable resistance switch comprising a rotatable casing having two longitudinal compartments adapted to contain resistance liquid and having a division wall with passage therethrough for retarding the flow of liquid from one compartment to the other, a tapering conducting element mounted in one compartment and extending longitudinally of said compartment, conducting heads for the casing with one of the heads carrying the conducting element, an arbor projecting axially from one head and provided with manipulating means, a mutilated gear wheel carried by the arbor, a rack bar engaged by the gear wheel and provided with means urging it in one direction, and said rack bar being provided with a circuit terminal, another circuit terminal in the path of the first-named circuit terminal, another rack bar carried by the firstnamed rack bar and a retarding gear train in position to be engaged by the secondnamed rack bar, and said second-named rack bar being of a length to escape from the gear train before the contacts engage, the resistance devices and retarding mechanism being provided with an inclosing box having a face plate through which the arbor extends and is there accessible.

10. A variable resistance switch provided with a rotatable casing having an intermediate longitudinal perforated division wall and conducting heads at the ends, a tapering conducting element carried by one head and extending toward the other, and means for moving the casing about its longitudinal axis, said casing being adapted to contain a quantity of resistance liquid to progressively rise along the tapering portion of the conducting element or recede therefrom as the element is turned with one compartment or the other uppermost.

11. A variable resistance switch provided with a rotatable casing having intermediate longitudinal perforated division walls and conducting heads at the ends, a tapering conducting element carried by one head and extending toward the other, and means for moving the casing about its longitudinal axis, said casing being adapted to contain a quantity of resistance liquid to progressively rise along the tapering portion of the conducting element or recede theret'rom as the element is turned with one compartment or the other uppermost, the said means for moving the casing having retarding means associated therewith to slow the movements of the casing.

12. A variable resistance switch provided with a rotatable casing having an interme diate longitudinal perforated division wall and conducting heads at the ends, a tapering conducting element carried by one head and extending toward the other, and means for moving the casing about is longitudinal axis, said casing being adapted to contain a quantity of resistance liquid to progressively rise along the tapering portion of the conducting element or recede therefrom as the element is turned with one compartment or the other uppermost, the said means for moving the casing having retarding means associated therewith to slow the movements of the casing, and said retarding means having circuit closing means associated therewith for short circuiting the resistance means to complete the closure of the circuit.

18. A variable resistance switch comprising means for the progressive cutting in or out of resistance, means for retarding the movement of the means "for cutting in and out the resistance, short circuiting means for the resistance, and means for accelerating the movement oi? the means for cutting out the resistance at the terminal portion of its movement to cause a rapid closure of the short circuiting means.

1-1. A variable resistance switch comprising a rotatable casing having conducting heads and insulation between the heads and adapted to contain a quantity of resistance liquid, a tapering conducting element within the casing carried by one head and terminating close to but out of contact with the other head, means for rotating the casing, short circuiting means for the resistance for effectively cutting the latter out of circuit when the circuit is fully closed, means for retarding the opening and closing movements of the switch, and means for causing the acceleration of the closing movement at the terminal portion thereof.

In testimony, that I claim the foregoing as my own, I have hereto allixed my signature in the presence of two witnesses.

WILLIAM BLAUKNELL GROSSLAND.

Witnesses A. J. FRAUNTIIAL, C. A. SCHULTZ,

Gopies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C. 

